Explosive cartridge



Aug. 22, 1933. D. B. MccLoUD EXPLOSIVE CARTRIDGE Filed Oct'. 27, 1952 2Sheets-Sheet l Patented A-ug. 22, 1933 UNITED STATES .PATENT OFFICEApplication October 27,

4 Claims.

This invention relates to an explosive cartridge, more particularly acartridge or measured charge unit containing an'explosive adapted foruse in open pit or strip mining and quarrying opera- 5 tions. Anexplosive cartridge of the character to which the present inventionrelates may comprise an outer cloth covering or container made of canvasor other suitable material and filled with a fibrous, granular, orpowdered Carbonaceous material of porous character, harmless in itself,but whenv impregnated or saturated with a penetrative combustionsupporting element of a certain character, such as liquid oxygen, alsoharmless by itself, becomes readily combustible and highly explosive.

The particular explosive to which the present invention relates is knownas liquid oxygen explosive, because of itsy constituent mixture ofporous carbonaceous material and liquid oxygen, 2Q and for brevity it iscommonly referred to as L O. X. There are many differently proportionedmixtures of inflammable' materials and liquid oxygen, all within thesame general class or category and properly identied as liquid oxymableabsorbents for liquid oxygen explosive cartridges are lamp blacks,carbon blacks, and certain types of granular carbon.

Certain mixtures are more sensitive to shock or impact than others, somebeing of exceedingly high sensitivity, and premature explosions duringblast loading operations have caused the loss of a number of lives.There are many theories as to the cause of these-premature explosions,some of which are conflicting, but a common theory is'that suchexplosions are caused by certain shocks orimpacts occurring accidentallyas Well as through deliberate manipulation during the loadingoperations. It is known that liquid voxygen explosives made of finelydivided lamp blacks the like are considerably more sensitive to shockthan other typesA of this explosive made from coarser granular carbonsor other larged particled materials. The nely divided lamp blacks arethe most desirable on account of their ideal absorbent properties, themore inl timate mixture of carbon and oxygen made possible by theirminute structure, and their superior oxygen retaining qualities, all ofwhich advantages promote the efficiency of the explosive., Thus, on theone hand, it will be seen that the mixture including the granular orcoarser particled carbonaceous material is less sensitive to shock andconsequent premature explosion, butv gen explosive, but the most widelyused iniiam-` 1932. Serial No. 639,757 (ci. 1oz-6) l tions, while on theother hand, the more powerful and eicient mixture comprising the finelyparticled lamp blacks is accordingly more sensitive to impact andpremature explosion.

Heretofore, the apparent object of muchpf the research work inconnection with the liquid oxygen explosives has beento discover anddevelop an ideal carbonaceous absorbent materiall of relatively lowsensitivity and inherently safe from the standpoint of impact andprevention of premature explosions. The addition of moisture and inertde-sensitizing materials to the active ingredients of liquid oxygenexplosive cartridges has been advocated as a means of decreasinghandling hazards by making the explosive less sensitive to shock. Suchpractice, however, while decreasing the possibility of prematureexplosion, also detracts from the blasting power and efficiency of theexplosive. Also, as hereinbefore stated, the relatively coarse particledcarbonaceous absorbent material reduces the sensitivity of the cartridgebut at the same time correspondingly decreases its eiciency.

Since its introduction a few years ago, liquid oxygen explosive, or L.O. X., as it is more commonly termed, has been used quite successfullyby several of the leading coal strippers and in other mining orquarrying operations for the blasting and removal of overburden, as wellas in other industrial operations, it being found very eicient for thepurpose but, as above noted, requiring due care and skill in preparationand loading operations to prevent premature explosion.

In the past, and more particularly in strip mining or quarryingoperations, in which liquid oxygen explosive has been used as abovenoted, it has been the customary practice to sink vertical holes in theoverburden and then load the holes with the explosive cartridges, stemand detonate. More recently, drilling machines have been produced todrill horizontal holes ranging from four to seven inches in diameter andup to eighty feet in length. Said machines are placed in the pit or cutand the holes are drilled horizontally in the lower portion of theoverburden to whatever dimensions desired, within the above named limit.The explosive cartridges are then pushed into these holes, stemmed andshot; thereby breaking up the overburden so that it can be handledeiciently by power shovels employed to remove it. The principaladvantage claimed for this new blasting procedure, which is manipulatedfrom within thepit or cut, is that it is more economical and eicientthan the old procedure involving the use of vertically operated drillsand with all the blasting handled on the high Wall or bank.

' In the use of liquid oxygen explosive in horizontal drill holes fourinches for more in diameter and over thirty feet deep, diiiiculties areinvolved which the present invention overcomes. As hereinbefore stated,the explosive cartridge as finally prepared for use is impregnated orv-the time they are removed from their bath of liquid oxygen and exposedto ordinary temperatures, otherwise the evaporation of the liquid oxygenwill reach the point where the explosive eiiiciency of the cartridge isgreatly impaired.

In the case of vertical drill holes, cartridges can y be dropped downtherein in rapid succession, and a comparatively heavy charge loaded andstemmed in the holes easily within the prescribed thirty minute loadingtime. However, in the case of horizontal holes, the process of loadingis somewhat slower, because the explosive cartridge must be pushed inthe hole by means of a rod or pole, sometimes one cartridge at a time;and, instead of merely shoveling in the stemming, as in the verticalholes, the stemming must be pushed into the hole in a like manner afterthe cartridges, which operation greatly increases the time required forloading as compared with the vertical holes according to the olderpractice.

There is still another condition to be coped with, and that is thefrequentpresence of moisture or water within the drill holes, due either,to' seepage or the use of water in the drilling operation, or both.Therefore, due to its extremely cold temperature, the cartridge isliable to freeze to the Wall of thedrill hole. This freezing lodgementis more'liable to occur in a horii attempt to dislodge, by forciblemeans, a cartridge frozen as above set forth, or otherwise lodged in adrill hole as is liable to occur if the cartridge is relatively flexibleor distortable so as to be deformed by pushing the same with a pole orramming tool during the loading operation.

Experimentation and subsequent practical development have produced thepresent invention, one of the objects of which is to provide for theutilization of the iinely divided carbonaceous material, preferably lampblack-or carbon black, to secure the admittedly high efficiency in aliquid oxygen explosive cartridge by providing shock absorbing andcushioning means in a Wrapper or container whereby to minimize andprevent premature explosions to a reasonably safe degree.

Another object of the invention isto secure rigidity and preservation ofform and surface contour of the cartridge.

A still further object is to retard evaporation of the liquid oxygen andthereby prolong the saturated life of the explosive and at the sameytime yprovide effective insulation whereby to maintain the extremelycold temperature Within the cartridge and prevent transmission of thesame to the exterior thereof.

With the foregoing objects in view, the invention consists broadly inmeans for carrying out the several provisions noted; in the productionof a cartridge having a specially combined stiffening and formpreserving, shock absorbing and cushioning, and insulative lining orsheath; and in the structural parts and combinations and arrangements ofsuch parts as hereinafter described and set forth with particularity inthe appended claims.

In the accompanying drawings, illustrating a practical adaptation of theinvention,-

Fig. 1 is a perspective view of a completed explosive cartridgeembodying the present invention;

Fig. 2 isa longitudinal section, taken on or about the line 2-2 of Fig.1;

Fig. 3 is a transverse section, on an enlarged scale, the line ofsection being indicated at 3-3 in Fig. 2;

Fig. 4 is a longitudinal sectional view of the cartridge container withthe ller removed and in the condition preparatory to receiving thefiller;

Fig. 5 is a plan view of the shock absorbent and insulative lining blankas preliminarily prepared and detached from the cartridge;

Fig. 6 is an edge view of an end closure and padding disc for thecartridge; and

Fig. 7 is a face view of said disc.

Referring now to the adaptation of the invention as illustrated in thedrawings, the numeral 10 designates a cloth bag made of osnaburg, duck,canvas, or other suitable fabric of like tensile strength andcharacteristic porosity, to serve as an outer form producing andretaining cover possessing the requisite flexibility in itself forfacilitating its application to the cartridge and in maintaining thenormal shape of the cartridge with the aid of an additional element inthe form of a liner or sheath constituting the more essential structuralfeature of the present invention and to be presently described.

Prior to the present invention the outer casing of. a liquid oxygenexplosive cartridge was, in many cases, only filled with the absorbentcarbonaceousmaterial which was packed therein so as to limit theflexibility of the cartridge to some extent, and varying according tothe density or compactness of the filler, but, of course, withoutabsolute rigidity. In the use of cartridges thus constructed andprepared premature explosions have occurred in the hole loadingoperations, due to shocks or impacts involved in forcible dislodgementof cartridges stuck in the bore holes. Aside from the liability oflodging engagement of the cartridge due to irregularities in the drillhave occurred in the hole loading operations, due to the freezing of thecartridge to the wall in cases where there is excessive moisture orwater present.

More recently, stiffening of the cartridge has been attained byproviding the outer cloth casing or covering with a liner comprising asheet of material, such as chipboard, cardboard, juteboard, strawboard,or what is commonly known as -pressboard, or the like, of sufficientflexibility so as -to be bent for insertion in the outer covering orcontainer conformably to the contour of the cartridge. While the lineror sheath within the covering stilfens and adds rigidity to thecartridge to a considerable degree, thereby facilitating the sliding ofthe cartridge along a horizontal drill hole, and, by its insulative andcushioning qualities, effectively reducing the liability of prematureexplosions in the loading operation and other handling of the cartridge,the measure of safety is not complete, and there is still room forimprovement in the provisions for the safe handling and use of theexplosive. To this end, therefore, as hereinbefore pointed out, theinvention has for its principal object to secure and maintain amplerigidity of the cartridge and, further, to provide cushioning meansrendering the cartridge less liable to premature explosion by accidentalor incidental shocks in the ordinary handling of the explosive instorage and transportation, as well as in loading operations, and at thesame time provide for insulation to prevent rapid evaporation of theliquid content of the cartridge and also prevent freezing of thecartridge to the wall of the drill hole.

The'cartridge produced in accordance with the present invention isprovided with a suitable liner or sheath of material having bothcushioning and insulating qualities, such as corrugated or embossedchipboard, pulpboard, cardboard, juteboard, strawboard; or the like, thepreferred practical material being the ordinary commercial corrugatedstraw or paper board used for linings and in the construction of packingboxes, cartons, and the like.

The ideal lining material is the single faced corrugated board or, inother words, the ordinary commercial material comprising a flat plainsheet or layer l1a and a corrugated sheet or layer 11b which isattached, where its alternate convolutions occur, to the at sheet by asuitable adhesive, the material, of itself, being a regular commercialcommodity and not constituting any part of the present invention exceptin the particular use for which it is employed.

Preferably the corrugations run lengthwise of the cartridge and thecorrugated layer portion of the liner is disposed outwardly or next tothe outer casing or container 10, this being for the dual purpose offacilitating the bending of the liner to conform to the curvature of thecartridge the major portion of which is substantially cylindrical, andto afford insulative air spaces between the liner and the outer casingor container, the corrugations also functioning as a cushion toeffectively absorb shocks.

In the usual and more preferred form of the cartridge it is generallycylindrical in shape 'throughout its extent except that it is formedprojectile-like or with a tapered nose at one end, by which formationthe cartridge more readily enters the drill hole and its movement intoexploding position is greatly facilitated. The liner, or cushioning andinsulating sheath, as it may be also properly called, is formed in theoriginal blank so as to conform to the tapered end portion of the outercasing or container 10, which end portion of the casing, designated bythe numeral 12, is accordingly shaped and closed.

The liner or cushioning and insulating sheath 11 is originally producedpreferably in the form of a substantially rectangular blank, as shownmore clearly in Fig. 5 of the drawings, one end portion of the blankbeing serrated to provide a multiplicity of wedge-shaped portions 13,said tapered portions or fingers, as they may be termed, being insuflicient number to readily conform to the n'shape of the tapered noseportion 12 of the cartridge casing or container 10, and the ends of saidportions 13 being either somewhat rounded, as at 14, or they mayobviously be pointed or cut off squarely, as the particular formation ofthe ends is of no material consequence, for in some cases the meetingends of the portions 13 when the liner is applied in the outer casingmay. overlap, while in other cases the end portions may not quite meet.In fact, there is but little liability of accidental explosion bycontact in the region of the extreme end of the nose portion 12 of thecartridge with an obstruction, and, by having an opening between the.ends of the liner portions 13, the saturation of the absorbent fillerof the cartridge is facilitated. Owing to the disposition of thecorrugations of the liner or sheath 11 lengthwise of the cartridge,thereby making it diicult to bend the tapered ngers or tongue portions13 at the bases thereof, the blank is preferably scored transversely, asat 13B.

In the preferred construction the lining blank 1l is made of a width sothat when fitted conformably inside the outer casing or -container bag10 there is a space between the meeting 1ongitudinal edges of the blankforming a longitudinal slot at one side of the lining, as shown moreclearly at 15 in Fig. 4 of the drawings. The purpose of this slot is toobviate the necessity for perforating or aperturing the blank, whichwould be necessary in 'order to permit penetration and saturation of theabsorbent contents of the cartridge when placed in the soaking box orchamber of the device in which the liquid oxygen is supplied. The slot15 may be relatively narrow, in practice averaging about one-eighth ofan inch in width, by which dimension ample opening is provided fortheentrance of the liquid-oxygen during the saturation process, and yetexudation of the carbonaceous absorbent material is practicallyprevented, both before and after saturation.

In the production of the cartridge, after the outer casing or containerbag 10 has the cushioning and insulating lining or sheath 11 placedtherein it is filled with the absorbent material, indicated at 19 inFigs. 2 and 3 of the drawings, either the extremely ne particled orcoarse granular, as the case may be, and suitably packed according tothe nature of the filler and the required density, after which a disc 16of material similar to that comprising the lining 11 is placed in theopen end of the outer casing and against the end of the lining, saiddisc 16 preferably being of a diameter substantially the same as theinterior diameter of the bag 10 and the corrugations being disposedoutwardly. After the disc is in place the end portion 17 of Vthe bag 10extending beyond the lining material is gathered and tied by a cord or apiece of copper wire, as at 18, and shown more clearly in Figs.

-1 and 2 of the drawings, said gathered end portion 17 affording aconvenient hand hold for carrying the cartridge.

By the provision of the corrugated lining and the similarly corrugatedend closure disc 16, the impregnated or saturated cartridge may behandled with considerably less care than cartridges of this type ofexplosive not so provided, with but little or no liability of accidentalor prema- .ture explosion from ordinary shocks due to impacts in thehandling thereof. The lining of the present invention also greatlyminimizes the liability of premature explosion in the loading operationby practically eliminating the possibility of the cartridge lodging inthe drill hole, as its insulating quality prevents radiation of theextremely cold temperature and consequent freezing to the wall in caseswhere the cartridge is applied'in a drill hole containing excessmoisture or water resulting from the drilling operation or seepage ashereinbefore pointed out. The further advantage of the insulatingfeature of the lining material or sheath is the prevention of the rapidevaporation of the liquid oxygen, thereby prolonging the eflicientlyactive explosive life of the cartridge, which is especially desirable ina cartridge of this character, particularly in loading horizontal drillholes and the like whereby more time and care are required in placingand positioning the cartridge than in the vertical drill holes in whichthe cartridges are merely dropped instead of having to be pushed intoplace.

Experimentation has shown conclusively that sensitivity to shock in aliquid oxygen explosive cartridge is materially reduced by encasing theexplosive ingredients in a relatively rigid shock absorbing sheath,whether the carbonaceous absorbent ller is relatively ne or coarseparticled. Actual tests of the explosive in an impact machine haveproven that a cartridge made of a finely divided lamp black, which isconceded by all authorities as having the highest absorbent propertiesand eciency and being the most sensitive to shock in a cartridge of thischaracter, if encased in a cushioning sheath of the character of thatset forth in the foregoing specification, is approximately one-half assensitive to impact and shock as a cartridge containing an identicalcarbonaceous filler but not protected by such a sheath or cover. Hence,the practical advantage of a cartridge produced in accordance with thepresent inventionpis clearly apparent, regardless of the particledconsistency of the absorbent carbonaceous filler, but especially mostadvantageous in the use of the extremely fine particled ingredients.

Obviously, various carbonaceous materials mayA be used in the productionof the cartridge, and in different degrees of fineness and density ofpacking, as hereinbefore described, and the outerl casing and liningmaterials may be varied considerably while maintaining the combined formpreserving, shock absorbing, and insulating qualities, all within thespirit and scope of the invention as defined by the appended claims. Theinvention, therefore, except in the use of liquid oxygen as thesaturating element, is not limited to the specic materials norconstruction and arrangement shown in the drawings.

tive air spaces, and functioning as a cushioning pad between the outercloth casing and the filler ingredients of the cartridge.

2. A liquid oxygen explosive cartridge of the character described,generally cylindrical in body formation, said cartridge comprising anouter rel taining casing of cloth, a carbonaceous absorbent fillerimpregnated or saturated with liquid oxygen, and a lining of stiffeningand insulating sheet material interposed between said outer cloth casingand saturated absorbent ller, the longitudinal edges of said liningsheet meeting in spaced relation whereby to provide a slotted opening inthe lining for the impregnation and saturation of the carbonaceousfiller with the liquid oxygen.

3. A liquid oxygen explosive cartridge of the character described,generally cylindrical in body formation and having a taperedprojectile-like end portion, said cartridge comprising an outerretaining casing of cloth, a carbonaceous absorbent ller impregnated orsaturated with liquid oxygen, and a lining of stiifening and insulatingsheet material interposed between said outer cloth casing and saturatedabsorbent ller, the longitudinal marginal edges of said lining sheetmeeting in spaced relation whereby to provide a longitudinally slottedopening in the lining for the impregnation and saturation of thecarbonaceous filler with the liquid oxygen, the end portion of saidlining being serrated to provide tapered portions meeting andcooperating conformably` with the tapered end portion of the outercasing.

4. A liquid oxygen explosive cartridge comprising a porous cloth outerform producing and retaining case and a carbonaceous absorbent DON s.MccLoUD.

